1. Field of the Invention
The present invention relates to a recording/reproducing apparatus in which an analog audio signal is encoded into a digital audio data and the digital audio data is stored in a semiconductor memory device.
2. Description of the Related Art
In recent years, a digital recording/reproducing apparatus has been put to practical use in various fields. Such a digital recording/reproducing apparatus converts an analog audio signal into digital data and stores the digital audio data in memory means. The use of a semiconductor memory as the memory means makes possible a random access to the digital audio data stored in the memory. A digital recording/reproducing apparatus including such a semiconductor memory is suitable particularly for a dictating machine, because it is required for a dictating machine to be able to reproduce an audio signal immediately after the signal was recorded, and to reproduce any arbitrary portion of the recorded signal.
FIG. 3 shows an example of a conventional digital recording/reproducing apparatus in which a semiconductor memory is used as memory means (Japanese Laid-Open Patent Publication No. 60-12591). The digital recording/reproducing apparatus utilizes an internal memory 21 and a memory pack 22. The memory pack 22 can be mounted in or dismounted from the apparatus at will. A digital audio data encoded in an encoding circuit 23 is first written into the internal memory 21 through an audio recording controller 24. When the internal memory 21 is filled with the audio data, the audio recording controller 24 changes the destination of the memory to which the audio data to be stored is transferred, whereby immediately subsequent audio data will next be stored in the memory pack 22. Accordingly, recording operations of the internal memory 21 and the memory pack 22 are carried out in series (cascade connection). The memory pack 22 has conventionally been used merely as a storage for compensating for the lack of capacity of the internal memory 21. The digital audio signal is read out from the internal memory 21 or the memory pack 22 and is converted into an analog audio signal by a decoding circuit 25.
In the above-mentioned conventional digital recording/reproducing apparatus, the memory pack 22 starts the recording operation after the internal memory becomes full. When the memory pack 22 becomes full, no audio data can be stored in the apparatus. However, if the storage capacity of the memory pack 22 is exhausted during the recording operation, the sound recording is interrupted while the memory pack 22 is exchanged, which has caused a problem.
If two memory packs 22 are mounted at the same time in the digital recording/reproducing apparatus, even though the first memory pack consumes its storage capacity, the audio data can immediately be transferred into the second memory pack so as to continue the recording. Moreover, the first memory pack can be exchanged by the time the second memory pack is filled with the audio data, so that a continuous recording can be realized for a long time period without any interruption. However, in this case, two pairs of a connector and an interface circuit are required for mounting two memory packs in the apparatus, which causes other problems of making a larger sized apparatus and of rising cost.